1. Field of the Invention
The present invention relates generally to monodisperse mesoporous silica microspheres, and more particularly to a method of forming monodisperse mesoporous silica microspheres by evaporation-induced self-assembly of surfactant templates in aerosols.
2. Description of the Prior Art
Evaporation-induced self-assembly (EISA) of arnphiphilic molecules (e.g., surfactants and block copolymers) within aerosols and thin films has been recently demonstrated to be a powerful and flexible method for synthesizing ordered mesoporous silica particles and thin films, see Y. Lu, H. Fan, A. Stump, T. L. Ward, T. Reiker, C. J. Brinker, Nature, 1999, 398, 223; C. J. Brinker, Y. Lu, A. Sellinger, H. Fan, Adv. Mater., 1999, 11, 579; and Y. Lu, R. Ganguli, C. A. Drewien, M. T. Anderson, C. J. Brinker, W. L. Gong, Y. X. Guo, H. S oyez, B. Dunn, M. H. Huang, J. I. Zink, Nature, 1997, 389, 364, the entire contents and disclosures of which are hereby incorporated by reference. The previous synthesis of mesoporous silica particles using aerosol EISA has been limited to particle sizes of roughly 1 μm or smaller possessing a relatively wide particle size distribution. There are many applications where larger mesoporous particles with high monodispersity are needed or would be highly beneficial. Several examples include: controlled delivery, where monodispersity may ensure uniform delivery rates; biosensing based on flow cytometry, where monodisperse spheres with sizes of several μm could serve as ‘cell mimics’; and photonic bandgap materials, where high monodispersity, periodicity and control of dielectric constant are critical factors, see T. Buranda, G. M. Jones, J. P. Nolan, J. Keij, G. P. Lopez, L. A. Sklar, J. of Phys. Chem. B, 1999, 103, 3399; and J. D. Joannopoulos, P. R. Villeneuve, S. Fan, Nature, 1997, 386, 143, the entire contents and disclosures of which are hereby incorporated by reference. Thus, there is still a need to provide a mechanism for producing such large mesoporous particles.